Broadly, the present invention relates to an apparatus for clearing stored material, such as silage, from the top of a stack of such material. The present invention particularly relates to an apparatus for extracting silage from the top of a silo container having a round cross-section, which comprises a discharge or clearing means which extends from the marginal region of the silo to its central region and is carried by a cantilever device or boom supported on the silage and rotatable about the vertical silo axis, a projection or suction fan or blower for conveying the cleared silage from the silo, and a motor drive.
Apparatus for clearing stored material from the top of a stack of such material should as far as possible be capable of being used with all types of feed stuffs, such as chopped grass, maize, and other short-cut material, without having to make modifications in the discharge or clearing means. The density of the stored material differs according to the grade or quality thereof, and the cohesion or the bonding of the individual parts of the material with one another is largely dependent on the cut length of the material. More especially stored grass or other dried silage, which is introduced with the short-cut type loaders which are being increasingly used, is strongly intertangled, since the crop, in this type of harvesting procedure, is cut in irregular lengths. Such types of feeding stuffs cannot be satisfactorily discharged with conventional discharge apparatus. These devices have a much too low discharge capacity. An additional problem is that they detach the crop or material irregularly from the stack of feeding stuff, as a result of which clogging effects frequently occur.
One group of the known top-extraction devices has a cantilever device or boom, on which is arranged a revolving chain which is fitted with milling tools. This milling chain revolves in such a way that its bottom run facing the stack or pile of silage is moved towards the centre of the silo, so that the feed is detached from the stack or pile and is transported towards the middle, from which it is thereafter removed. Such top-extraction devices with a revolving milling chain, however, have the disadvantage that the silage, and other short-cut material, is not sufficiently detached from the pile. The regularly revolving milling tools comb out the material still connected to the pile in such a way that it is no longer collectible by the following tools. Moreover, portions of the material are detached in the form of flat layers without being sufficiently distributed, as a consequence of which clogging effects occur, expecially at the inlet to the fan or blower. These known devices accordingly have a low output efficiency and show a great tendency for disruptions.
Another group of top-discharge devices is also known, which use one or two screw conveyors for the clearing and further transport of the silage, said conveyors being provided with tools on their circumference. The upper side of these screw conveyors is enclosed by a casing, so that the discharged material can be carried away. The tools detach and separate the material from the pile or stock and the screw conveyor blade or blades transport the said material towards the center, from which it is ejected or extracted by suction.
However, these top-extraction devices also exhibit the disadvantage that they are not well suited for clearing or carrying away short-cut material provided by loaders. The milling tools comb the adhering material in a circumferential direction and the worm or screw conveyor blades are not able to pick it up or carry it away. The material is only carried away in very small quantities and in a very irregular manner, depending on the cohesion of the separate portions of the material. The engaging action of the milling tools during the subsequent revolving of the milling boom is impaired from time to time, as a result of which the output yield is also further reduced.